Bisigi themes are very special place in the hearts and minds of Ubuntu users. I also like these Bisigi Themes it's look awesome.Bisigi Themes for Ubuntu
Bisigi constitutes a collection of great 15 themes for Ubuntu. here you can see some previews of Bisigi themes.

Note: I have not checked on Ubuntu 11.10 Oneiric Ocelot, I think it is not working on Ubuntu 11.10 Oneiric Ocelot, If you want you can try it. But it is working Perfectly on Ubuntu 11.04.